Breech mechanism for automatic firearms



May 16, 1944. P. DE KIRALY E1- AL 2,348,790

BREECH MEGHANISM FOR `IJ'IOMLTIC FIREARMS Fued Nov. 1s, 1939 Patented May 16, 1944 BREECH MECHANISM FOR AUTOMATIC FIREARMS Paul de Kirly and Jzsef Kucher, Budapest,

Hungary; vested in the Alien Property Custodian Applicationv November 13, 1939, Serial No. 304,226 In Hungary December 12, 1938 1 Claim.

This invention relates to automatic rearms of the kind wherein the bolt is operated by the cartridge shell recoiling under the pressure of the powder gases. after having overcome the inertia of the bolt, and wherein. in order to increase the inertia of the bolt and thus prevent premature opening of the same, the bolt comprises two members connected by a lever hereinafter referred to as an accelerator lever having two arms of diiferent lengths. the lever being pivoted on the bolt proper, its longer arm loosely connected to the inertia member of the bolt, the shorter arm engaging a stationary abutment in the breech casing of the arm, thus imparting, under pressure of the cartridge shell, to the inertia member relative movement at increased velocity.

The present invention comprises an improved construction of such bolt mechanism, according to which the two armed accelerator lever, adapted for retaining without any additional component parts, itself and the two members of the bolt in their unlocked relative position during the recoil and return movement of the bolt, reduces at the same time the pressure and friction between the inertia lever and the breech casing. cau-sed by the pressure of the closing spring.

The invention also comprises means for lessening friction between the moving parts, during their rearward and forward travel, and their guide, that is the breech casing, caused by the tendency of the return spring to rotate the inertia lever into its initial locked posit-ion, thus causing lateral pressures on the walls of the receiver. One embodiment of the invention is illustra-ted in the accompanying drawing, in which Fig. l is a longitudinal section through the bolt in its closed position,

Fig. 2 is a longitudinal section through the bolt during its rearward movement,

Fig. 3 is a cross sectional view on the line 3-3 of Fig. 1 taken through the straight guide of the bolt and through the abutment of the inertia lever,

Fig. 4 is a cross section, showing the seat of the handle in the striker.

Fig. 5 shows means for lockingthe cap of the breech-casing to the latter, by means oi a lever controlled by the recoil spring.

Fig. 5A illustrates a detail of the device shown in Fig. 5.

Fig. 6 is a sectional View taken on the line 6-6 of Fig. 4 showing the nre-control ring mounted on the breech-casing and its spring pawl, cut out from the body of the lire-control ring.

(Cl. l12--3) Fig. 6A is a side View of the device shown in Fig. 6.

Fig. 7 is a cross sectional view on the line 'l-l of Fig. 4 taken through breech-casing, bolt, striker and handle, showing the manner in which the handle sits in the striker and is guided in the breech-casing.

The barrel l is firmly connected, by a screwthread to the breech casing 2 comprising a hollow cylinder, the rear of which is closed by a cap.

Behind the magazine and ejection openings, and close to them, an inverted U shaped part 6 sits on the breech casing, its flanges passing through the wall of the saine and forming the straight guide for the bolt. Below this straight guide B is arranged in a cut in the lower wall of the breech casing the abutment 'i of the accelerator lever. The straight guide 6 and abutment l are held in their position by the ring B encircling both parts and being connected by the screw 9 to the trigger plate.

In the cylindrical interior of the breech casing is placed the breech bolt of the non-rigidly locked type which supports the bottom of the cartridge shell mostly by its inertia and which in the usual way is allowed a rectilinear movement of suitable length relatively to the breech casing and is controlled by the main spring 5.

The breech bolt consists of three parts; the bolt proper I4 and striker i5 which are connected by the accelerator lever IB pivoted in the rear end of the bolt I4.

The principle o this main lever is known from other inventions (see British Specification No. 26,783 A. D. 1912). The'two armed inertia lever is pivoted in the rear part of the bolt I4. Its short arm b projects downward from the bolt whilst its long arm a is in loose connection with the striker. When the bolt I4 moves backward under the pressure of the powder gases, the lower, short arm of the inertia lever hits the abutment 1, whereupon its long arm pushes back with increased velocity the striker I5 relatively to the bolt I4.

Accordingly, the weight of the striker asserts itself more eiectively than if the striker moved only with the speed of the breech bolt, in proportion to the existing leverage, or the proportion in which stand the lengths of both arms of the two armed inertia or locking lever.

In other inventions of this kind of breech bolt mechanism either the striker and the inertia 1ever are held in their unlocked or in their locked positions by some separate spring controlled sear,

for moving out of the way of the lower arm of the inertia lever during the return movement of the latter.

In our invention we avoid this complication by giving a third arm c to the inertia lever, which can be called an extension of the short arm b. This third arm c of the inertia lever is adapted for keepingr the inertia lever I6 and with it the striker I during the repeating movement of the bolt, in their cocked position, by the end of this Yarm c sliding on the wall of the breech casing and thus hindering any forward rotation of the ineri tia lever, until the arm c on its return way has passed the abutment 'I.

The longer is the extension c, the less is its pressure on the wall of the breech casing. A convenient length of the extension c is chosen (Figs. 1 and 2) at which this pressure remains within convenient lim-its.

Considering that the main spring 5 constantly strives during the recoiling and return movement of the bolt to cause forward rotation of the inertia lever I6 so that the extension c of its short arm b is constantly pressed against the wall of the breech casing, thus causing undesired friction, we arrange in the end of the extension c of the arm b of the inertia lever I6 a roller II in order to avoid the undesired friction.

Another source of undesired friction is the fact that the same force which presses against the wall of the breech casing the end of the extension c of the arm b of the inertia lever, strives to lift the pivot of the accelerator lever, thus pressing the bolt and the striker against the upper wall of the breech casing 2. Another undesired friction is thus caused which also must be eliminated as far as possible. We accomplish this by employing another roller I8, sitting in the top of the striker, preferably near to its forward end and approximately above the roller I'I in the extension c of the arm b of the accelerator lever I6, when in its cocked position.

Thus, when the pressure of the powder gases forces the bolt backward, the main lever I5 pushes back the striker I5 into its cocked position and keeps it there, without the help of other parts, during the whole subsequent backward and forward movement of the bolt.

When, toward the end of its forward movement the extension c of the arm b of the inertia lever has passed the abutment 1, the inertia lever I6 is allowed to rotate forward under the pressure o! the main spring 5 the striker advances and fires the cartridge in the barrel.

A handle I9 is connected with the striker, being passed therethrough.

The trigger mechanism may be of the conventional design.

The firing pin 39 is inserted between bolt I4 and striker I5 and held in correct position by its wing 3|, fitting into the recess in which sits the roller I8-of the striker I 5. This disposition allows very easy change of the ring pin in case of damage.

Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is:

An automatic firearm comprising a casing,'a barrel secured to said casing, a breech movable in said casing, said breech comprising a supporting element adapted to perform a recoil movement, a two-armed lever pivotally mounted on said supoprting element, an actuating element movably disposed in said casing, the first arm of said lever being disposed in contact with said actuating element, resilient means urging said actuating element against said supporting element in a direction opposite to that of the recoil movement thereof, an abutment adapted to engage the second arm of said lever and tilt the same, whereby said actuating element is a displaced relative to said supporting element, a control member forming an extension of said second arm, guiding means adapted to engage said control member to maintain said lever in tilted position during the recoil movement, a iiring pin operatively connected to said actuating element, whereby upon the return movement of the breech, said lever after clearing said guiding means, is suddenly thrown forward under the influence of said resilient means to restore the original relative position between said supporting element and actuating element, whereby the ring pin is suddenly projected with respect to said supporting element, a second guiding means of inverted U- shape, said casing being provided with an opening, said U-shaped second guiding means being secured to the outside of said casing, the prongs of said U-shaped second guiding means projecting through said opening into the casing and serving to guide said actuating element: said abutment being provided with iiaps extending outside said casing, and a ring member encircling the outside part of said U-shaped second guiding means and said flaps, and securing the same to said casing.

PAUL DE KIRLY. JZSEF KUCHER. 

